Wild birds learn what to avoid eating by watching others

Wild birds watch and learn from others what to eat – and what to avoid eating – according to a new study led by the University of Helsinki. The research has produced the first evidence of birds using observations to dodge toxic or distasteful prey.

“We’ve known for a long time that predators, like birds, associate brightly colored warning signals with the danger of eating certain prey types,” explained study co-lead author Rose Thorogood.

“However, we’ve never been able to demonstrate in the wild how predators learn about these aposematic prey advertisements. If predators do not recognize the signal, then the prey are highly vulnerable to naive predators.”

“This is a big problem that prey face each year when juvenile predators arrive. Since aposematism is widespread in nature, we wanted to solve this problem in a real-world setting.”

Liisa Hamalainen, a doctoral student at the University of Cambridge, conducted field research at the Madingley Wood site in Cambridgeshire, UK. The team combined field experiments with social network analyses to investigate social information transmission among bird predators.

“Here, we investigate how social information about defended prey and their palatable mimics spreads in a wild blue tit and great tit population,” explained the study authors.  

“We use artificial prey, a well-established experimental method to test how predators learn about novel prey signals and combine this with technological advances that now make it possible to identify individuals’ foraging choices.” 

The goal was to test how quickly birds learn to discriminate between tasteful and distasteful food, and whether they use social information about the foraging experiences of others during this learning process.

The experts set up pairs of bird-feeders, including one that dispensed brightly-dyed almond flakes that were naturally tasty and one that dispensed almond flakes with additives to make them disgustingly bitter.

The blue tits and great tits gathered around the feeders to select their food, and also observed feeding attempts by others.

“Our results show that birds use social information to discriminate between unpalatable and palatable food,” wrote the researchers. “This suggests that social transmission among predators can influence attack rates on defended prey and their mimics, and therefore shape the selection environment experienced by prey.”

“Our results may help resolve how costly prey defenses are maintained despite influxes of naïve juvenile predators, and suggest that accounting for social transmission is essential if we are to understand coevolutionary processes.”

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer